Biodiversity Patterns of Early–Middle Ordovician Marine Microphytoplankton in South China

Palaeogeography, Palaeoclimatology, Palaeoecology 299 (2011) 318–334

Contents lists available at ScienceDirect

Palaeogeography, Palaeoclimatology, Palaeoecology

journal homepage: www.elsevier.com/locate/palaeo

Biodiversity patterns of Early–Middle Ordovician marine microphytoplankton in South China

Kui Yan a,b,c,⁎, Thomas Servais c, Jun Li a,b, Rongchang Wu a, Peng Tang a,b a Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39, East Beijing Road, 210008 Nanjing, China b State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing 210008, China c FRE 3298 du CNRS, Géosystèmes, Université de Lille1, SN5, USTL, F-59655 Villeneuve d'Ascq, France article info abstract

Article history: Based on new materials from six sections and all available literature data, new diversity curves are presented Received 22 June 2010 for the phytoplankton (acritarchs) from South China, covering the Early–Middle Ordovician interval, when Received in revised form 18 October 2010 the Great Ordovician Biodiversification Event took place. The total diversity curve and the origination data Accepted 9 November 2010 imply that a major radiation of the phytoplankton occurred during the analysed interval. A peak of the total Available online 13 November 2010 acritarch diversity curve appears in the A. suecicus graptolite biozone. The diversity changes vary in the different parts of the investigated area, most probably depending on the position of the analysed sections on Keywords: the carbonate shelf or the slope, reflecting diversity differences due to the position on an inshore–offshore Acritarchs Early–Middle Ordovician transect. South China The Early–Middle Ordovician diversity pattern of the phytoplankton is compared with those of several marine Biodiversity invertebrate groups. Compared with the diversity curve peak of the acritarchs, the conodonts and brachiopods Sea-level changes reached their highest diversities before the acritarchs, while the highest diversity of the chitinozoans appears slightly later. The graptolites show two peaks during the Early–Middle Ordovician, while the trilobites diversity curve shows a peak only in the Sandbian. The different fossil groups, such as chitinozoans, conodonts, graptolites, brachiopods and trilobites show therefore different evolutionary patterns to that of the acritarchs, that are not yet fully understood, and correlations are so far difficult. The acritarch diversity changes can partly be compared to the local sea-level changes from four sections in South China. At a larger scale, the acritarch radiation coincides with a general transgression. At a regional or local scale, correlations are not straightforward, pointing out that more detailed data, based on both acritarch studies and more precise sea-level investigations, are necessary. © 2010 Elsevier B.V. All rights reserved.

1. Introduction Although more than 40 papers were focused on the Ordovician acritarchs in South China, the Ordovician radiation of acritarchs is far The Great Ordovician Biodiversification Event (GOBE) is one of the from being completely understood. Most paper focused on biostratig- most significant radiations of marine organisms during Earth history, raphy (Li et al., 2002b,c), and a few highlighted the importance of the showing a rapid increase in biodiversity and an important ecological South Chinese palaeogeography for palaeobiogeographical considera- evolution (Harper, 2006; Servais et al., 2008, 2009, 2010). Webby et al. tions of the acritarchs (Li, 1989, 1991; Li and Servais, 2002; Servais et al., (2004a) published a synthesis on the Ordovician radiation which 2003). In the last decade, several papers analysed the biodiversity of the documented the biodiversity curves of approximately 25 fossil groups. South Chinese phytoplankton in the Ordovician. Tongiorgi et al. (2003) In the Proterozoic and Palaeozoic fossil record, most acritarchs are implied that the acritarch diversity changes in the Dawan Formation considered to represent marine phytoplankton cysts which constitute from the Daping section in Yichang may be affected by inshore–offshore the fossil record of one part of the base of the marine food chain. and climatic trends. Servais et al. (2004) reviewed the global Ordovician Servais et al. (2008) related ‘the Ordovician plankton revolution’ to acritarch literature and illustrated an acritarch diversity curve of South the diversification of the phytoplankton as evidenced by the record of China. Li et al. (2004) discussed the inshore–offshore trend of acritarch acritarchs and prasinophytes. distributions and acritarch diversity variations from seven South China localities during the interval of the deflexus–suecicus graptolite biozones. Yan et al. (2005) discussed the implication of the acritarch diversity ⁎ Corresponding author. Nanjing Institute of Geology and Palaeontology, Chinese changes from the Meitan Formation from the Honghuayuan section, Academy of Sciences, 39, East Beijing Road, 210008 Nanjing, China. Tongzi. Li and Yan (2006) reviewed the Ordovician acritarch diversity E-mail addresses: [email protected] (K. Yan), [email protected] (T. Servais), [email protected] (J. Li), [email protected] (R. Wu), changes in South China and pointed out an acritarch biodiversity event [email protected] (P. Tang). in the Early–Middle Ordovician. The publication of Li et al. (2007)

0031-0182/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.palaeo.2010.11.012 K. Yan et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 299 (2011) 318–334 319 focused on the Ordovician acritarch diversity counted from the prepared for diversity analysis herein. Acritarch diversity curves of literature and sea-level change in China. South China analysed from the literature data are also presented. In recent years, marine biodiversity changes from China were investigated in the project on the ‘Origination, Radiation, Extinction 2. Material and methods and Recovery in the Geological History’ (e.g., Rong et al., 2007) concerning several taxonomic groups of Ordovician marine organisms 2.1. New material in South China, such as graptolites (Zhang et al., 2007), brachiopods (Zhan et al., 2005, 2006), and trilobites (Zhou et al., 2007). The In order to understand acritarch diversity patterns in South China, diversity of other fossil groups has also been investigated, such as that 160 samples for palynological and diversity analysis were collected from of chitinozoans (Paris et al., 2004; Wang and Chen, 2004), and six sections, 45 samples from the Meitan Formation, Honghuayuan conodonts (Wang and Wu, 2007; Wu et al., 2010). section in Tongzi (Guizhou); seven samples from the Guanyinqiao Ordovician microphytoplankton biodiversity curves and their impli- section in Qijiang (Chongqing); 14 samples from the Dacao Formation cations have been discussed from several other palaeocontinents. Vecoli and Yingpan Formation, Houping section in Chengkou (Chongqing); 34 and Le Hérissé (2004) provided a detailed Ordovician acritarch diversity samples from the Dawan Formation, Huanghuachang section in Yichang curve from the northern margin of South Gondwana. They inferred that (Hubei); nine samples from the Dawan Formation, Daping section in the acritarch diversity curve is hardly compared to the second order sea- Yichang (Hubei); and 51 samples from the Ningkou Formation, level change, and the acritarch diversity changes would be well Huangnitang section in Changshan (Zhejiang) (Fig. 1). correlated to that of the chitinozoans during the Ordovician. Molyneux During the Early and Middle Ordovician, from northwest to (2009) suggested an acritarch diversity evolutionary pattern based on southeast, the South China tectonic plate comprised the Yangtze investigations from deep-water settings in northern England. Ordovician Platform, the Jiangnan Slope, and the Zhujiang Basin (Chen et al., 1995) acritarch diversity curves from the palaeocontinent Baltica have been and Early–Middle Ordovician rocks were deposited in southwest– studied by Hints et al. (2010). Diversity patterns of Ordovician acritarchs, northeast band-like zones (Zhang et al., 2002). The six sections chitinozoans and scolecodonts show some similarities in Baltica and the investigated here are located in different lithofacies. The Honghuayuan acritarch diversity curve can be related to that of other fossil groups in section in Tongzi, the Guanyinqiao section in Qijiang and the Houping some extent (Hints et al., 2010). section in Chengkou are located in an inner-shelf mud–carbonate belt The objective of the present paper is to analyse the Early–Middle during the latest Early–earliest Middle Ordovician which is character- Ordovician acritarch diversity in South China and its relationship with ised by the dominance of carbonate sediments mixed with argillaceous the diversity of other fossil groups and the sea-level change. The and sandy intercalations (Zhang et al., 2002). The Huanghuachang and acritarch assemblages from six sections in South China have been Daping sections in Yichang are located in a shallower outer-shelf

105˚ 110˚ 115˚ 120˚ SHAANXI JIANGSU HENAN

Min 13 4 12 Han River 24 11 ANHUI Jialing Nanjing 14 SICHUAN River Hefei HUBEI

River 8 Chengdu 7 6 River 9 Wuhan Yangtze 30˚ 30˚ 5 120˚ 25 CHONGQING Yalong ZHEJIANG Chongqing 1 3 2 17 15

River 18 16 Nanchang 26 19 10 Changsha HUNAN JIANGXI GUIZHOU FUJIAN 20 Fuzhou Guiyang YUNNAN 21 27 22 29 28 23 20˚ 30 GUANGXI 20˚ 0 100 200km Kunming 105 110˚ 115˚

Fig. 1. Locality map of the Floian–Darriwilian sections where acritarchs have been studied in South China. 1. Huangnitang, Changshan (Yin and Playford, 2003; this work); 2. Hengtang, Jiangshan (Xu et al., 2002); 3. Chenjiawu, Yushan (Huang, 1991; Huang et al., 1994; Xu and You, 2001), 4. Chenjiazhuang, Yunxi (Sun, 1999); 5. Tonghaikou, Xiantao (He, 1998); 6. Daping, Yichang (Playford et al., 1995; Tongiorgi et al., 1995, 1998, 2003; Yan et al., 2010; this work); 7. Huanghuachang, Yichang (Li, 1991; Li et al., 2004; Lu, 1987; Tongiorgi et al., 1998; Yan et al., 2010; this work; Yin, 1994, 1995; Yin et al., 1998; Zhong, 1981, 1987) 8. Jiangyangping, Zigui (Brocke, 1997a,b; Brocke et al., 1999, 2000); 9. Xintan, Zigui (Xing and Liu, 1985); 10. Datuo, Jishou (Li, 1990a,b; Li et al., 2004); 11. Gaoqiao, Ziyang (Hu, 1986); 12. Liangjiaqiao, Zhenba (Fu, 1986); 13. Zhaojiaba, Ningqiang (Fang, 1990; Li, 1991; Li and Yuan, 1998; Li et al., 2004); 14. Houping, Chengkou (Yan et al., 2010; this work); 15. Wangjiazai, Youyang (Brocke, 1997a,b; Brocke et al., 1997, 1999, 2000); 16. Datianba, Xiushan (Brocke, 1997a,b; Brocke et al., 1997, 1999, 2000); 17. Guanyinqiao, Qijiang (Yan et al., 2010; this work); 18. Ganxi, Yanhe (Li, 1991); 19. Honghuayuan, Tongzi (Li, 1987; Li et al., 2000, 2004; Yan and Li, 2005; Yan et al., 2010; this work); 20. Huanghuachong, Guiyang (Li, 1991; Li et al., 2002a, 2004); 21. Wuliguan (Li, 1991), Sandu; 22. Xiayangao, Sandu (Xu, 1995, 1996, 1999, 2001; Xu et al., 1995); 23. Yangnengzai, Sandu (Li, 1991); 24. Tanjiagou, Guangyuan (Fang, 1990); 25. Emeishan (Xing, 1980); 26. Shuanghe, Changning (Li, 1991); 27. Wannike, Luquan (Fang, 1986a); 28. Yinchunli, Luquan (Fang, 1986a); 29. Renmingqiao, Wuding (Gao, 1991); 30. Ercun, Kunming (Fang, 1986a,b; Li, 1991; Li et al., 2004). 320 K. Yan et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 299 (2011) 318–334 carbonate-mud belt during the late Early Ordovician–earliest Darri- The acritarch assemblage in the eobifidus graptolite biozone wilian (Zhang et al., 2002). The Huangnitang section in Changshan is consists of 38 species assigned to 24 genera. In the deflexus graptolite located in a mud–silt belt of the Jiangnan Slope. biozone the maximum diversity of 79 species assigned to 40 genera is All samples were treated in the Palynological Laboratory of the reached, before a diversity drop to 59 species and 32 genera within Nanjing Institute of Geology and Palaeontology following standard the suecicus graptolite biozone. In the hirundo graptolite biozone, the palynological techniques. Samples were observed under a Zeiss acritarch diversity continues to reduce to 56 species assigned to 28 Axioskop2 Plus light microscope. The slides and residues are housed genera. Within the austrodentatus graptolite biozone, the acritarch in the Nanjing Institute of Geology and Palaeontology, Chinese assemblage consists of 33 species assigned to 23 genera. The acritarch Academy of Sciences, Nanjing, China. The stratigraphical ranges of assemblage within the intersitus graptolite biozone is composed of 16 all species from these six sections have been drawn in Figs. 2 and 3. species assigned to 13 genera. The acritarch diversity curves therefore show a high acritarch 2.2. Literature data diversity during the deflexus to suecicus graptolite biozones, and lower diversities during the hirundo and austrodentatus graptolite biozones, In addition to the new investigation, the Chinese literature has also and even lower during the eobifidus to lower deflexus graptolite been entirely reviewed. biozones (Fig. 4). The maximum acritarch diversity is present in the Li et al. (2002b) first reviewed all Chinese acritarch studies, listing middle deflexus graptolite biozone in the Meitan Formation, Hong- over 100 articles published in the last three decades. Over 50 papers huayuan section. described acritarch assemblages from the Ordovician, most of them concerned South China and the Early–Middle Ordovician. For the 3.1.2. The acritarch diversity from the Meitan Formation, Guangyinqiao present study, all papers on the South China Ordovician acritarchs section in Qijiang have been reviewed. Acritarch assemblages from 30 sections have Thirty seven acritarch species assigned to 26 genera are present in been recorded in about 40 studies (including Master or PhD theses) the Meitan Formation in Qijiang from five samples. Data are only (Fig. 1). A database including the taxonomic information (species and available from the deflexus and suecicus graptolite biozones. genus name, author), locations, and the stratigraphical ranges of all The acritarch assemblage in the deflexus graptolite biozone is formally described or fully identified species was established. Only composed of 26 species assigned to 18 genera, and 23 genera and 29 those species and genera with microphotographs in the publications species within the suecicus graptolite biozone (Fig. 4). have been entered in the dataset. Taxa in open nomenclature are not taken into account. 3.1.3. The acritarch diversity from the Dawan Formation, Huanghuachang All taxa were biostratigraphically attributed to the graptolite section in Yichang biozones of Chen et al. (2001, 2003) and Zhang et al. (2007). Most The palynomorph assemblages from 34 samples of the Dawan Ordovician literature of South China concerned taxonomy and Formation, Huanghuachang section in Yichang include 94 species biostratigraphy and only provided stratigraphic information at the assigned to 35 genera. formation level. Most papers provided stratigraphic information at The acritarch assemblage in the eobifidus graptolite biozone in the the level of graptolite biozones that were, however, used inconsis- Dawan Formation includes 18 genera and 48 species. The acritarch tently (e.g., Li et al., 2010; Tongiorgi et al., 2003; Yan and Li, 2005). diversity slightly decreases to 32 species allocated to 18 genera within the deflexus graptolite biozone, and then reaches its peak within the 2.3. Methods suecicus graptolite biozone with 33 genera and 81 species. The acritarch diversity subsequently declines to 44 species assigned to 22 Diversities are measured from the six sections at species and genera genera within the hirundo graptolite biozone and 45 species allocated levels (Fig. 4). The total diversity and normalised diversity (species and to 23 genera within the clavus graptolite biozone. The acritarch genera per graptolite biozone) are also measured including material diversity rises again to 26 genera and 59 species within the from the six sections (Fig. 5) and from the literature (Fig. 6). The austrodentatus graptolite biozone. normalised diversity used herein follows Cooper (2004). Rarefied Four peaks are obviously shown in the diversity curves per sample diversity curves are also provided (Figs. 5 and 6) and rarefaction was (Fig. 4). The four peaks appear in the suecicus, the middle of the hirundo, calculated using the software package PAST (Hammer et al., 2001) the lower clavus and the upper clavus graptolite biozones (Fig. 4). The (Figs. 7 and 8). To estimate evolutionary changes, originations (o), maximum acritarch diversity is present in the middle suecicus graptolite extinctions (e) and turnovers (o+e) per graptolite biozone are also biozone in the Dawan Formation, Huanghuachang section. given in this paper (Figs. 5 and 6). 3.1.4. The acritarch diversity from the Dawan Formation, Daping Section 3. Results in Yichang The acritarch diversity is a little lower in the Dawan Formation, 3.1. Acritarch diversity changes in the six sections from South China Daping Section, than in the Huanghuachang section. 71 species assigned to 27 genera from nine samples are present in the Dawan A total of 127 species assigned to 45 genera have been recorded Formation, Daping section. from the six sections (Honghuayuan section in Tongzi, Guanyinqiao There are 31 species allocated to 17 genera in the deflexus graptolite section in Qijiang, Houpin section in Chengkou, Huanghuachang and biozone and 34 species allocated to 13 genera acritarchs in the suecicus Daping sections in Yichang and Huangnitang section in Changshan) in graptolite biozone. Within the clavus graptolite biozone, the acritarch South China (Figs. 2 and 3). Because the six sections are located in diversity reaches 15 genera and 35 species. The highest acritarch different sedimentary facies during the Early–Middle Ordovician, the diversity of this section is present within the austrodentatus graptolite acritarch assemblages and their diversity vary from these sections. biozone which displays 25 genera and 57 species.

3.1.1. The acritarch diversity from the Meitan Formation, Honghuayuan 3.1.5. The acritarch diversity from the Dacao and Yingpan formations, section in Tongzi Houping section in Chengkou The palynomorph assemblage from 45 samples in the Meitan Fourteen samples were collected from this section, and 52 species Formation in Tongzi consists of 99 species assigned to 42 genera. The assigned to 29 genera were recognised in the Dacao and Yingpan diversity curves are shown in Fig. 4. formations, Houping section. l (2004b) al. i.2. Fig. tairpi agso h lint oe arwla ciacsfo i etosi ot hn pr ) rpoiebooe ae on based biozones Graptolite 1). (part China South in sections six from acritarchs Darriwilian lower to Floian the of ranges Stratigraphic 489Ma 472Ma .

Lower Ordovician Middle Ordovician Series Tremadocian Floian Dapingian Darriwilian Stages pe Yangtze Upper austrodentatus tintinniformis flabeliformis linnarssoni murchisoni intersitus copiosus eobifidus sinensis suecicus filiformis deflexus hirundo Region clavus artus ? Graptolite Biozones dentatus austro- Jiangnan Region ‘ -’ ‘’ approximatus Adelograptus taojiangensis Clonograptus ‘’ teretiusculus fasciculatus protobifidus matanensis fruticosus parabola victoriae suecicus deflexus elegans imitatus ellesae anglica clavus Zhejiangensis sinicus Dw3 Dw2 Dp3 Dp2 Dw1 Dp1 Tr3 Tr2 Fl3 Fl2 Tr1 Fl1 Stage Slices 4b 1b 2b 3b 4a 3a 1a 2a 4c 1c 2c 1d Time Slices

1 Ve ryhachium estrellit? ae 2 Micrhystridium acum brevispinosum 3 Cristallinium dentatum 4 Dictyotidium sp. 2 5 Picostella turgida 6 Veryhachium symmetricum 7 Acanthodiacrodium tasselii 8 Petaloferidium bulliferum 9 Veryhachium lairdii 10 Veyhachium sp. 11 Acanthodiacrodium burmanniae 12 Aureotesta clathrata simvar. plex 13 Lophosphaeridium citrinipeltatum 14 Polygonium sp. 15 Rhopaliophora palmata 16 Rhopaliophora pilata 17 Stelliferidium striatulum 18 Striatotheca pricipalis parva 19 Veryhachium trispinosum 20 Cymatiogalea granulata 21 Dactylofusa velifera brevivar. s 22 Micrhystridium acuminosum 23 Pachysphaeridium rhabdocladium hn ta.(2007) al. et Zhang 24 Baltisphaeridium spp. 25 Leprotolypa evexa 26 Micrhystridium henryi 27 Petaloferidium florigerum 28 Polygonium gracile 29 Leiosphaeridia spp. 30 Peteinosphaeridium tenuifilosum 31 Baltisphaeridium sp.3.

tg lcsbsdon based slices stage , 32 Peteinosphaeridium robustiramosum 33 Sacculidium inornatum 34 Baltisphaeridium microspinosum 35 Coryphidium bohemicum 36 Multiplicisphaeridium sp. 1 37 Sacculidium macropylum 38 Athabascaella playfordii 39 Multiplicisphaeridium dikranon 40 Rhopaliophora florida 41 Rhopaliophora membrana egtö ta.(2009) al. et Bergström 42 Ampullula princeps 43 Arbusculidium filamentosum 44 Peteinosphaeridium sp. 45 Tectitheca additionalis 46 Baltisphaeridium sp.1 47 Rhopaliophora mamilliformis 48 Acanthodiacrodium sp. 49 Ampullula crassula 50 Ampullula erchunensis 51 Ampullula suetica n iesie ae on based slices time and , 52 Baltisphaeridium calicispinae 53 Baltisphaeridium denticulatum 54 Baltisphaeridium kunmingense 55 Baltisphaerosum christoferi 56 Baltisphaerosum sp. 57 Dasydorus cirritus 58 Liliosphaeridium kaljoi 59 Pachysphaeridium pachyconcha 60 Peteinosphaeridium coronula 61 Peteinosphaeridium dissimile 62 Pirea sinensis

eb et Webby 63 Sacculidium peteinoides

64 Solisphaeridiumsp. cf. S. solare

.Yne l aaoegah,Pleciaooy aaoclg 9 21)318 (2011) 299 Palaeoecology Palaeoclimatology, Palaeogeography, / al. et Yan K. 334 321 –

322 K. Yan et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 299 (2011) 318–334

7 12 Ordovicidium elegantulum Ordovicidium

126 Webby et Pachysphaeridium P. pachyconcha P. cf. sp. Pachysphaeridium

125 Coryphidium elegans Coryphidium

2 1 4 sp. 2 sp. Multiplicisphaeridium

3 12 Pachysphaeridium kjellstromii Pachysphaeridium

2 12 sp. 2 sp. Orthosphaeridium

121 sp. 1 sp. Orthosphaeridium

120 Pirea levigata Pirea

119 Multiplicisphaeridium rayii Multiplicisphaeridium

118 Baltisphaeridium hirsutoides Baltisphaeridium

117 Baltisphaeridium filosum Baltisphaeridium

116 Dasydorus microcephalus Dasydorus

5 11 Baltisphaeridium klabavense Baltisphaeridium , and time slices based on

4 11 Baltisphaeridium coolibahense Baltisphaeridium

Pirea ornata Pirea 3 11

Dicrodiacrodium ancoriforme Dicrodiacrodium 12 1

1 1 1 Baltisphaeridium longispinosum longispinosum longispinosum Baltisphaeridium

110 eurc gradata ? Tenuirica

109 Peteinosphaeridium exornatum Peteinosphaeridium

108 Pachysphaeridium striatum Pachysphaeridium

107 Leiosphaeridia laevigata Leiosphaeridia

106 Leiofusa simplex Leiofusa

0 1 5

sp. 1 sp.

Cymatiogalea Bergström et al. (2009)

104 Baltisphaeridium granosum Baltisphaeridium

103 sp.2. Cymatiosphaera

2 10 sp.1. Cymatiosphaera

1 10 Tenuirica T. wadeiae T. cf. sp. ? Tenuirica

0 10 Striatotheca monorugulata Striatotheca

Loeblichia heterorhabda Loeblichia 99

98 Liliosphaeridium intermedium Liliosphaeridium

97 sp. 1 sp. Dictyotidium

96 sp.2. Baltisphaeridium

, stage slices based on 95 Baltisphaeridium ritvae Baltisphaeridium

94 Baltisphaeridium podboroviscense Baltisphaeridium

Arkonia tenuata Arkonia 93

92 ? sp. ? Tenuirica

91 Athbascaella penika Athbascaella

90 Ampullula composta Ampullula

89 Veryhachium trisulcum Veryhachium

Striatotheca transformata Striatotheca 88

Leiofusa tumida Leiofusa 7 8 Zhang et al. (2007)

Barakella rara Barakella 6 8

5 8 Vavrdovella areniga Vavrdovella

84 sp. 2 sp. Pterospermella

83 sp. 1 sp. Pterospermella

Leiofusa somniculata Leiofusa 82

Leiofusa fusiformis Leiofusa 81

0 8 sp. Leiosphaeridia

9 7 Multiplicisphaeridium M. irregulare M. cf. sp. Multiplicisphaeridium

78 sp. Micrhystridium

77 Lophosphaeridium rarum Lophosphaeridium

76 Baltisphaerosum Baltisphaerosum bystrentos

75 Peteinosphaeridium angustilaminae Peteinosphaeridium

74 Peteinosphaeridium armatum Peteinosphaeridium

73 Multiplicisphaeridium irregulare Multiplicisphaeridium

72 Baltisphaeridium fragile Baltisphaeridium

71 Baltisphaeridium brevifilicum Baltisphaeridium

0 7 Leiosphaeridia tenuissima Leiosphaeridia

69 Tongzia meitana Tongzia

8 6 ysheiimgotlandicum cf. Synsphaeridium

67 sp. 2 sp. Solisphaeridium

66 sp. 1 sp. Solisphaeridium

65 oipardu solidispinosum aff. Solisphaeridium

es Slic

Time 1d 2c 1c 4c 2a 4a 1a 3a 2b 1b 3b 4b

es Slic Stage Fl1 Tr1 Fl2 Fl3 Tr2 Tr3 Dp1 Dw1 Dp2 Dp3 Dw2 Dw3 sinicus Zhejiangensis clavus anglica ellesae imitatus elegans deflexus suecicus victoriae parabola fruticosus matanensis protobifidus fasciculatus teretiusculus ‘’ Clonograptus taojiangensis Adelograptus approximatus ‘’ ‘ -’ Jiangnan Region Jiangnan austrodentatus Graptolite Biozones Graptolite ? artus clavus Region hirundo deflexus filiformis suecicus sinensis eobifidus copiosus intersitus murchisoni linnarssoni flabeliformis

tintinniformis

austrodentatus Upper Yangtze

Darriwilian Tremadocian Floian Stages Dapingian

Series Middle Ordovician Middle Lower Ordovician Lower . 472Ma 489Ma Stratigraphic ranges of the Floian to lower Darriwilian acritarchs from six sections in South China (part 2). Graptolite biozones based on Fig. 3. al. (2004b) s

s Graptolite e Biozones

Tim

Stage

Slice

Series

Stages Honghuayuan Guanyinqiao Huanghuachang Daping Houping Huangnitang linnarssoni species genus species genus species genus species genus species genus species genus Dw3 4c 02040608002040010203001020 02040 60 80 0102030 0 20 40 60010200204001020 02010 0510 murchisoni .Yne l aaoegah,Pleciaooy aaoclg 9 21)318 (2011) 299 Palaeoecology Palaeoclimatology, Palaeogeography, / al. et Yan K. artus Dw2 4b

Darriwilian intersitus

austrodentatus Dw1 4a

clavus Dp3 Middle Ordovician Middle 3b Dp2 hirundo Dp1 3a

Dapingian 472Ma suecicus Fl3 2c deflexus Fl2 eobifidus 2b

Floian filiformis Fl1 approximatus 2a

copiosus acritarch diversity in sample acritarch diversity per graptolite biozone 1d sinensis Tr3

Lower Ordovician Lower 1c tintinniformis – 334 Tr2

Tremadocia 1b

flabeliformis Tr1 1a 489Ma

Fig. 4. Ordovician acritarch diversity curves calculated for the six sections from South China investigated in this study. Graptolite biozones based on Zhang et al. (2007), stage slices based on Bergström et al. (2009), and time slices based on Webby et al. (2004b). 323 324

s Total and normalized Rarefied diversity Origination Extinction Graptolite diversity curves (genera) Turnover Biozones

Time

Stage

Slice Slices 0 50 100 010203003060 03060 03060

Series

Stages

linnarssoni Dw3 4c murchisoni .Yne l aaoegah,Pleciaooy aaoclg 9 21)318 (2011) 299 Palaeoecology Palaeoclimatology, Palaeogeography, / al. et Yan K. artus Dw2 4b

Darriwilian intersitus

austrodentatus Dw1 4a

clavus Dp3 Middle Ordovician Middle 3b Dp2 hirundo Dp1 3a

Dapingian 472Ma suecicus Fl3 2c deflexus Fl2 eobifidus 2b

Floian filiformis Fl1 approximatus 2a

copiosus 1d Total diversity (species) Total diversity (genera) Normalized diversity (species) sinensis Tr3 Normalized diversity (genera ) Species origination Genera origination

Lower Ordovician Lower Species extinction Genera extinction Species turnover Genera turnover 1c

tintinniformis Number of samples – 334

Tr2

Tremadocia 1b

flabeliformis Tr1 1a 489Ma

Fig. 5. Ordovician acritarch diversity curves of South China from six sections. Graptolite biozones based on Zhang et al. (2007), stage slices based on Bergström et al. (2009), and time slices based on Webby et al. (2004b). Error bars represent the conﬁdence interval at 95%. Total and normalized Rarefied diversity

s e Origination Extinction Turnover Graptolite diversity curves (genera) Biozones

Time

Stag 0 100 200 300 400 0102030 050100150050100200150 0 50 100 150 200 250 300

Slices

Slice

Series

Stages

linnarssoni Dw3 4c murchisoni

artus Dw2 4b 318 (2011) 299 Palaeoecology Palaeoclimatology, Palaeogeography, / al. et Yan K.

Darriwilian intersitus

austrodentatus Dw1 4a

clavus Dp3 Middle Ordovician Middle 3b Dp2 hirundo Dp1 3a

Dapingian 472Ma suecicus Fl3 2c deflexus Fl2 eobifidus 2b

Floian filiformis Fl1 approximatus 2a

copiosus 1d sinensis Tr3

n Total diversity (species) Total diversity (genera) Normalized diversity (species)

Lower Ordovician Lower 1c Normalized diversity (genera) Species origination Genera origination

tintinniformis – Species extinction Genera extinction Species turnover Genera turnover 334 Tr2 Diversity after Servaiset al . 2004 Numbers of literature Tremadocia 1b

flabeliformis Tr1 1a 489Ma

Fig. 6. Ordovician acritarch diversity curves of South China from the literature. Graptolite biozones based on Zhang et al. (2007), stage slices based on Bergström et al. (2009), and time slices based on Webby et al. (2004b). Error bars represent the conﬁdence interval at 95%. 325 326 K. Yan et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 299 (2011) 318–334

45 deflexus

40 suecicus

hirundo 35 austrodentatus

Specimens=310 eobifidus 30

clavus 25

Taxa

us 20 at im ox pr ap 15 intersitus

filiformis 10

0 800 1600 2400 3200 4000 4800 5600 6400 7200 Specimens

Fig. 7. Rarefaction curves of the generic diversity in function of occurrences, subdivided in the graptolite biozones. Datasets are from six sections in South China.

The first acritarch assemblage recorded in this section is present The acritarch diversity curves per sample show three peaks in the in the approximatus graptolite biozone consisting of 29 species Houping section which appear in the approximatus, the eobifidus and assigned to 19 genera. A lower diversity is observed in the filiformis the upper hirundo graptolite biozones (Fig. 4). graptolite biozone with 18 species allocated to 10 genera. The acritarch diversity rises to 16 genera and 23 species in the eobifidus 3.1.6. The acritarch diversity from the Ningkuo Formation, Huangnitang graptolite biozone, and then decreases to 14 species assigned to 12 section in Changshan genera in the deflexus graptolite biozone. Within the suecicus As the Huangnitang section is located on the slope during the graptolite biozone, the acritarch assemblage is composed of 15 Early–Middle Ordovician, the acritarch assemblages are preserved genera and 20 species. A much higher acritarch diversity is recorded rather poorly, and the diversity is fairly low. Only 26 species assigned in the hirundo graptolite biozone, with 31 species assigned to 18 to 16 genera are present in the Ningkuo Formation in Changshan from genera. 51 samples.

suecicus 80

deflexus 70 eobifidus

60 hirundo

50 austrodentatus filiformis clavus

Taxa 40 Specimens=38 approximatus

intersitus

0 80 160 240 320 400 480 560 Specimens

Fig. 8. Rarefaction curves of the generic diversity in function of occurrences, subdivided in the graptolite biozones. Datasets are from the literature in South China. K. Yan et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 299 (2011) 318–334 327

The acritarch diversities show 14 species assigned to 8 genera The normalised diversity curves are also similar to the total within the suecicus graptolite biozone, 5 genera and 10 species within diversity curves in South China. Rarefied diversity changes are slightly the clavus graptolite biozone, and 11 genera and 22 species within the different and show the highest diversity in the intersitus graptolite austrodentatus graptolite biozone. The acritarch diversities in most biozone. samples are limited to not more than 10 species. The species origination curve fluctuates during the Floian to Lower Dapingian, and high originations occur in the approximatus, eobifidus, 3.1.7. The acritarch diversity from the six sections in South China and suecicus graptolite biozones. The high extinctions and turnovers Before comparing with the acritarch diversity changes counted of species are present in the suecicus, and austrodentatus graptolite from the literature, we first summarise the diversity changes biozones. The origination, extinction and turnover curves of genera discussed in the six sections (Fig. 5). are much flatter than that of species. In our study, the oldest acritarch assemblage appears in the early Floian approximatus graptolite biozone, but from one section only, 4. Discussion with a diversity of 29 species assigned to 19 genera. The assemblages recorded in the filiformis graptolite biozone in the same section 4.1. The acritarch diversity pattern in South China display a diversity of 18 species assigned to 10 genera. The acritarch diversity increases quickly to 70 species assigned to 31 genera in the It is difficult to compare the diversity trends from the six sections eobifidus graptolite biozone data from three sections available. The because of the different palaeoenvironmental settings, as we discuss number of genera recorded in the deflexus graptolite biozone reaches later. However, the acritarch diversity per graptolite biozone shows its peak at 41, while the number of species increases to 97. The similar trends to the acritarch sample diversity from the six sections. number of species recorded in the suecicus graptolite biozone reaches The acritarch diversity trends vary from the different sections that its peak at 105, and the number of genera remains 41. In the overlying we collected from South China (Fig. 4). The acritarch diversity curve in hirundo graptolite biozone, the diversity is reduced, with 80 species the Honghuayuan section reaches its peak in the deflexus graptolite assigned to 39 genera. The clavus graptolite biozone continues the biozone, while that in the Guanyinqiao section increases from the diminishing trend of diversity with 59 species assigned to 25 genera. deflexus to the suecicus graptolite biozone (Fig. 4). The highest In the austrodentatus graptolite biozone, the diversity increases again, diversities occur in the suecicus graptolite biozone in the Huanghua- with 85 species assigned to 34 genera. Diversity decreases sharply in chang section and in the austrodentatus graptolite biozone in the the intersitus graptolite biozone, with 27 species assigned to 16 Daping section as well as in the Huangnitang section (Fig. 4). The genera. maximum acritarch diversity in the Houping section is present in the Normalised diversity is a little lower than the total diversity, but middle hirundo graptolite biozone (Fig. 4). It implies that the different the normalised diversity curves are similar to the total diversity acritarch diversity trends would be influenced by local environmental curves. The rarefied diversity curve is different from the total and changes and/or sea-level changes, as the six sections are located in normalised diversity curves, however. Rarefied diversity rises contin- different facies zones. Li et al. (2004) indicated an inshore–offshore uously from the filiformis to the hirundo graptolite biozone, and then gradient of Ordovician acritarch of the Yangtze Platform, with the drops in the clavus graptolite biozone. In the austrodentatus graptolite highest diversities on the shelf and lower diversities in nearshore and biozone, another peak of acritarch diversity occurs. slope facies. The acritarch diversity of the Huangnitang section is the High species originations occur in the eobifidus graptolite biozone, lowest in the six sections while the others are much higher. The while the high species extinctions are present in the austrodentatus Huangnitang section is located in the slope, and all others are located graptolite biozone. The high species turnovers appear both in the in the inner or outer shelf during the Ordovician period. eobifidus and austrodentatus graptolite biozones. The origination, The acritarch diversity curves from the six sections (Fig. 5) are extinction and turnover curves of the genera are slightly flatter than similar to those counted from the literatures (Fig. 6). All acritarch that of the species. diversity curves show a continuous increase from the lower Floian to the suecicus graptolite biozone, and then a diversity drop. However, 3.2. The acritarch diversity in South China from the literature the acritarch species diversity curve from the six sections has another peak in the austrodentatus graptolite biozone, perhaps because a In this work, we use the database that was discussed by Li et al. higher diversity occurs at Daping in the austrodentatus graptolite (2007) to analyse the acritarch diversity in South China (Fig. 6). 519 biozone. species assigned to 94 genera have been recorded in South China Rarefaction studies are often used in diversity analyses to reduce during the interval of the Floian to lower Darriwilian from about 40 the bias which is caused by sample collection. Tipper (1979) papers (including one unpublished master thesis and two unpub- suggested some limitations of the use of rarefaction analyses in lished PhD thesis). diversity studies, such as the similarity of the organisms, the same Although the oldest Ordovician acritarch assemblage appears in standard collection of the samples, and the similar environment in the early Tremadocian, we only analyse the acritarch diversity from which the organisms live. In our case, rarefied acritarch diversity the Floian to lower Darriwilian. 41 genera and 133 species occur in the curves show different trends to the total and normalised acritarch early Floian approximatus biozone. The acritarch diversity raised to diversity. But it is difficult to compare the tendencies with the 182 species assigned to 51 genera in the filiformis graptolite biozone, acritarch diversities in the different graptolite biozones by using and then to 69 genera and 296 species in the eobifidus graptolite rarefaction curves in our case, because the rarefaction curves in our biozone. The acritarch diversity continues to increase to 73 genera and case (Figs. 7 and 8) are crossed from each other, which implied that it 323 species in the deflexus graptolite biozone, and the peak of does not suit all the limitations suggested by Tipper (1979). diversity is observed in the overlying suecicus graptolite biozone, We also counted the sample numbers in the six sections and the where 402 species assigned to 84 genera have been recorded. The literature numbers on the Ordovician acritarch assemblage in South acritarch diversity declines in the hirundo graptolite biozone with 63 China per graptolite biozone (Figs. 5 and 6). The curve of the sample genera and 214 species. 58 genera and 196 species are described in numbers is similar to the acritarch diversity curves and so is the curve the clavus graptolite biozone, and then the diversity is reduced, with of the literature numbers. The maximum diversity occurs in the 54 genera and 192 species in the Darriwilian austrodentatus graptolite austrodentatus graptolite biozone in our study (Fig. 4), while the biozone. In the overlying intersitus graptolite biozone, the diversity maximum diversity occurs in the suecicus graptolite biozone in falls to lower levels with 31 species assigned to 24 genera. Tongiorgi et al. (2003) (see Fig. 3 in Li et al., 2007) in the Dawan 328 K. Yan et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 299 (2011) 318–334

Formation, Daping section. The acritarch diversity changes per from that of acritarchs with only one peak in the austrodentatus graptolite biozone are different between our material and that of graptolite biozone. It is thus difficult to compare the Ordovician Tongiorgi et al. (2003) in the Dawan Formation, Daping section, which acritarch and chitinozoan diversities in South China. More details on implies that the sample size would affect the study of acritarch the Ordovician chitinozoan diversities in South China are therefore diversity analysis. Raup (1976) found that the Phanerozoic diversity needed. curve would be linked to the volume of sedimentary rocks that have The diversity of conodonts from South China has been analysed in been preserved. Smith (2007) pointed out that diversity curves several locations (Wang and Wu, 2007; Wu et al., 2010). The diversity constructed from counting taxa in the rock record or literature record curves of conodonts from the Yichang area (Wang and Wu, 2007) are are seriously biased by unevenness of geographical and stratigraphical similar to those of the acritarchs in the Huanghuachang section, sampling effort. It is evident that regarding the Ordovician acritarchs Yichang (Fig. 9). They both reach their peaks at the deflexus–suecicus of South China, the sample numbers also cause a bias in acritarch and austrodentatus graptolite biozones. Wu et al. (2010) also diversity analyses. More work needs be done to reduce or avoid this discussed the conodont diversities from the Zitai Formation, Anhui sampling bias. Province, which probably present a transitional lithofacies between Although little work has been done on global acritarch diversity the Meitan and Dawan formations (Chen et al., 1995). These few (Servais et al., 2004; Strother, 1996; Tappan and Loeblich, 1973), the conodont diversity curves show the maximum diversity in the Ordovician regional acritarch diversity has been discussed in several deflexus graptolite biozone which reached the peak earlier than the palaeocontinents, such as South China (Li et al., 2007; Servais et al., acritarch diversity curves (Fig. 9). However, neither complete nor 2004; Tongiorgi et al., 2003; Yan et al., 2005), North Africa (Servais et detailed Ordovician conodont diversity curves have been established al., 2004; Vecoli and Le Hérissé, 2004), England (Molyneux, 2009), so far in South China. In order to compare the Ordovician acritarch and and Baltica (Hints et al., 2010). A clear acritarch diversity increase conodont diversities, more are needed regarding conodonts. occurs in the Ordovician. However, acritarch diversity trends show Zhang et al. (2007) analysed the Early–Middle Ordovician different patterns on different palaeocontinents (Servais et al., 2004, graptolite diversities in both the Yangtze Platform and the Jiangnan 2008). The acritarch diversity peak appears in the upper Floian to Slope. Two peaks appear in the graptolite diversity curves in South lower Dapingian in South China, but only in the Darriwilian in North China, which occur in the filiformis to eobifidus graptolite biozones Africa (Vecoli and Le Hérissé, 2004) and still later, in the Sandbian to (time slice 2b) and in the upper hirundo to clavus graptolite biozones Katian, in Baltica (Hints et al., 2010). (time slice 3b). The diversity pattern of the graptolites differs from The acritarch originations, extinctions and turnovers are also that of the acritarchs that show a diversity peak in the suecicus counted in our studies. In the six sections, high originations occur in graptolite biozone. Zhang et al. (2007) noticed that the graptolite the eobifidus and suecicus graptolite biozones and high extinctions diversity changes show different trends in the Jiangnan Slope and the occur in the suecicus and austrodentatus graptolite biozones (Fig. 5). Yangtze Platform that implies that the regionally distinct biodiversi- Different from the six sections, the high originations only occur in the fication patterns would be related to the environmental changes of eobifidus graptolite biozone and high extinctions occur in the each region. Similarly, the acritarch diversity changes also display austrodentatus graptolite biozone in South China counted from the variations in different regions which suggest that acritarch diversity literature (Fig. 6). We also found disparities of acritarch forms changes are related to the local environment changes (e.g., Li et al., increasing from the lower Floian. However, its detail should be 2004). studied in the future. The acritarch origination curves imply that an Zhan et al. (2005) recognised that the brachiopod radiation of acritarch biodiversity event happened in the lower Floian in South Ordovician began in the approximatus graptolite biozone and reached China. The high acritarch extinctions occur in the austrodentatus the first diversity peak in the eobifidus graptolite biozone. The graptolite biozone probably because the lithofacies changed to brachiopod diversity curve peak appears a little earlier than that of carbonate rock in South China in the Darriwilian. the acritarchs (Fig. 9). Furthermore, Zhan et al. (2006) analysed the brachiopod β-diversity in South China and pointed out that the first 4.2. Comparison of diversities with other fossil groups diversity peak of Ordovician brachiopod radiation occurred mainly in shallow water, normal marine benthic regimes and then moved to The Early–Middle Ordovician stratigraphical succession is largely deeper or shallower water. The brachiopod radiation in the Early– complete in South China, with numerous well exposed sections and Middle Ordovician shows thus a different pattern to that of the richly fossiliferous strata yielding a wide range of fossil groups. Marine acritarchs. ‘Biodiversity’ changes are investigated in the project on the ‘Origina- The trilobite diversity continues to increase from the Floian to the tion, Radiation, Extinction and Recovery in the Geological History’ Darriwilian and reached its maximum in the Sandbian (Adrain et al., (e.g., Rong et al., 2007) concerning several taxonomic groups of 2004; Zhou et al., 2007)(Fig. 9). As for other palaeocontinents, the Ordovician marine organisms in South China. In this project, the transfer from the Ibex Fauna to the Whiterock Fauna occurs also in the marine biodiversities from the latest Proterozoic–Palaeozoic–early Ordovician trilobites of China (Zhou et al., 2007). The complex Mesozoic in South China have been discussed in which the sustained radiation pattern of the Ordovician trilobites is difficult to compare radiation of the Ordovician was recognised (Rong et al., 2007). High with that of the acritarchs so far. origination rates are also shown (Rong et al., 2007). The marine food chain in the Ordovician would evolve to a Several diversity curves of marine invertebrates from the Early– complex trophic web. Servais et al. (2008) implied that an important Middle Ordovician that have been constructed in the past few years in revolution of the trophic structure of marine organisms had happened South China can be partly compared with acritarch diversity curves. in the Ordovician in which acritarchs may play an important role Fig. 9 shows the diversity curves of acritarchs, chitinozoans, being probably an important part of the base of the food chain. A conodonts, graptolites, brachiopods and trilobites in the Early–Middle better understanding of the diversity trends of different fossil groups Ordovician of South China. could provide a key to understand the Ordovician food chain. The diversity curve of Ordovician chitinozoans from South China However, the Ordovician acritarch diversity curves from South has been built up by Wang and Chen (in Paris et al., 2004) with a China can so far only partly be compared with those of other fossil continuous increase until the austrodentatus graptolite biozone groups (e.g. chitinozoans, conodonts, graptolites, brachiopods and (Fig. 9). Five biodiversity events of Ordovician chitinozoans from trilobites). Different macroevolutionary patterns may indicate the South China have been recognised (Wang and Chen, 2004). The evolution of different organisms in various ecotypes during the diversity curve of Ordovician chitinozoans from South China differs Ordovician radiation in South China (Zhan et al., 2006). s

Graptolite es Biozones acritarchs chitinozoans conodonts graptolites brachiopods trilobites

Time

Stag

Slic

Slice

Series

Stages 0 50 100110 0102030010 2030405060 0 20406080020406080 01020304050 linnarssoni Dw3 4c murchisoni

artus Dw2 4b 318 (2011) 299 Palaeoecology Palaeoclimatology, Palaeogeography, / al. et Yan K.

Darriwilian intersitus

austrodentatus Dw1 4a

clavus Dp3 Middle Ordovician Middle 3b Dp2 hirundo Dp1 3a

Dapingian 472Ma suecicus Fl3 2c deflexus Fl2 eobifidus 2b

Floian filiformis Fl1 approximatus 2a

copiosus 1d acritarchs: Total diversity (species) Total diversity (genera) Normalized Diversity (species) sinensis Tr3 Normalized Diversity (genera )

Lower Ordovician Lower 1c conodonts: Yichang (species) Yichang (genera) Shitai (species) Shitai (genera) tintinniformis – 334 graptolites: Upper Yangtze Region (species) Upper Yangtze Region (genera)South China (species ) Tr2

Tremadocian 1b Jiangnan Region (species) Jiangnan Region (genera) South China (genera) trilobites: Sampled Range-through flabeliformis Tr1 1a 489Ma

Fig. 9. Acritarch diversity curves compared with diversity curves of chitinozoans (Paris et al., 2004), conodonts (Wang and Wu, 2007; Wu et al., 2010), graptolites (Zhang et al., 2007), brachiopods (Zhan et al., 2005) and trilobites (Adrain et al., 2004; Zhou et al., 2007) in South China. 329 330 K. Yan et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 299 (2011) 318–334

4.3. Acritarch diversity and sea-level changes regional scale. Fig. 11 illustrates the diversity changes of the acritarch assemblages in relation with sea-level changes from four sections. There is currently an ongoing discussion if the sea-level changes Yan et al. (2005) analysed the Honghuayuan section, where the had an impact or not on the diversity of the phytoplankton. four diversity peaks and three drops recognised can be approximately A general transgression was recognised during the Early–Middle correlated to the four sea-level peaks and the three sea-level falls Ordovician in South China (Chen et al., 2003). More detailed curves have (Fig. 11A). The relative abundance changes of some acritarch taxa in been published recently based on a sequence stratigraphic analysis of the Honghuayuan section can also be correlated to the sea-level the sections in the southeastern part of the Upper Yangtze Platform (Su, changes (Yan et al., 2005). 2001) and lithofacies and sediment cycles (Liu, 2006). Liu (2006) The acritarch diversity curves show no obvious peak. However, it is recognised seven major regression events and analysed sea-level hard to decide the relationships between the local sea-level and changes in different lithofacies of South China (Shuanghe at Changning, diversity curves in the Houping section, Chengkou for insufficient Sichuan Province; Honghuayuan at Tongzi, Guizhou Province; Daping at samples (Fig. 11B). The acritarch diversity curves of another two Yichang, Hubei Province; Houping at Chengkou, Chongqing). sections in the Yichang area partly correspond to the local sea-level Similar to the previous studies (Li et al., 2007; Servais et al., 2004), curve (Liu, 2006)(Fig. 11C, D). The acritarch diversity curve in the the present study confirms the peaks of acritarch diversity of South Huanghuachang section shows four peaks that appeared in the China in the deflexus–suecicus and austrodentatus graptolite biozones suecicus, lower hirundo, lower clavus, and austrodentatus graptolite that correspond to transgressions in the early Floian, and early biozones. The acritarch diversity peak that occurred in the suecicus Darriwilian (Fig. 10). With rising sea levels, spreading of continental graptolite biozone can be correlated to that of the sea-level curves. But masses and increasing habitat space, the disparity of acritarchs the diversity trend with maximum diversity occurred during the fall increased rapidly during the Early–Middle Ordovician. Remarkably, in sea level in the hirundo graptolite biozone. The other two peaks of the rapid increase of acritarch assemblages in the Floian interval acritarch diversity occurred in the clavus and austrodentatus graptolite corresponds to the increase of new acritarch forms. biozones and can be correlated to that of the sea-level curves again. If it appears evident that at a global level (dataset from all continents) The acritarch diversity curve in the Daping section partly corresponds and at a large time scale (e.g., the entire Phanerozoic) sea level seems to to the local sea-level curve in the austrodentatus graptolite biozone. have an impact on the diversity of the phytoplankton, the picture is However, we have no idea to correlate them in the upper Floian– more complicated at the level of an individual palaeocontinent, or at a Dapingian interval because of a lack of samples.

g i Graptolite

e t Biozones

S acritarch diversity curves Sea-level changes linnarssoni Li et al. 2007 Su 2001 Liu 2006 Dw3 4c 0 20 40 60 80 100 0 100200300400 04080

n murchisoni LHLH

r artus

r i Dw2 4b

r intersitus

e Dw1 4a l austrodentatus

d i clavus Dp3

a 3b

g Dp2

n i hirundo

p a Dp1 3a

D 472Ma suecicus Fl3 2c deflexus Fl2

a eobifidus

l 2b

F filiformis Fl1 approximatus

n 2a

o copiosus

d r 1d

r sinensis acritarch genera diversity counted from six sections

e Tr3

w acritarch species diversity counted from six sections

i L acritarch genera diversity counted from literatures c 1c

d tintinniformis acritarch species diversity counted from literatures

e Tr2

T 1b

flabeliformis Tr1 1a 489Ma

Fig. 10. Acritarch diversity curves of South China (from the six sections, literatures and Li et al., 2007) compared with sea-level changes of South China. Sea-level curves after Liu (2006), and Su (2001). K. Yan et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 299 (2011) 318–334 331 A B

s sea-level acritarch a sea-level acritarch

r r change diversity change diversity

S PT SS DS SB 0 10 20 30 F PT SS DS SB 01020 4 1 3 LH s LH 2 u

γ a

β a

u α F

sue.

e 5

d 5m

10m a

C D

s sea-level acritarch s sea-level acritarch

r change diversity r change diversity

S PT SS DS SB 0102030 S PT SS DS SB 01020

. i LH LH

austro.

sue.

v 1

d u 5m 5m

Fig. 11. Acritarch diversity curves from Honghuayuan, Houping, Huanghuachang and Daping sections compared with sea-level changes. A. Meitan Formation, Honghuayuan section,

Tongzi, Guizhou, Ap,Bp,Cp and Dp represent the four peaks in diversity curves, αv, βv and γv represent the three valleys in diversity curves (based on Yan et al., 2005); B. Houping section, Chengkou, Chongqing; C. Dawan Formation, Huanghuachang section, Yichang, Hubei; and D. Dawan Formation, Daping section, Yichang, Hubei. 1. Darriwilian, 2. clavus,3. austrodentatus,4.intersitus,5.deﬂexus, SB. shale basinal, DS. deep subtidal, SS. Shallow subtidal, PT. Tidal ﬂat. Sea-level changes based on Liu (2006).

Yan and Li (2010) already recognised ten acritarch ecology In some cases in our studies, the acritarch diversity changes are assemblages in South China and indicated that acritarch diversity uncorrelated with the sea-level changes which can be explained by changes would be influenced by sea level or other ecological factors. several factors. These include the possibility that there are not enough 332 K. Yan et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 299 (2011) 318–334 samples to analyse the acritarch diversity changes, but also the Acknowledgments possibility that non-eustatic palaeoenvironmental factors led to the acritarch diversity changes. On the other hand, the establishment of We are grateful to Zhang Yuandong, Zhan Renbin, Wang Yi and sea-level curves is still in its early steps, and more investigations need Yuan Wenwei for their valuable comments on collecting samples and to be done before the regional sea-level curves are reliable and providing information about the six sections in South China. We also correlatable. As the sea-level curves probably need to be better thank Thijs R. A. Vandenbroucke for discussing the chitinozoan constrained, and because some bias is obviously present in the diversity pattern. We acknowledge the careful review by the two acritarch dataset, correlations between phytoplankton diversity and referees Stewart G. Molyneux (Keyworth, Nottingham) and Peter M. sea level are not yet straightforward. Sheehan (Milwaukee, Wisconsin). Yan Kui and Li Jun are grateful to Molyneux (2009) mentioned that the effect of sea-level changes several Chinese projects (NSFC40802006, 41072001, and LPS on acritarch diversity might be to shift the locus of maximum 2009404). Yan Kui acknowledges the Chinese Academy of Sciences acritarch diversity. The relationships between acritarch diversity and the FRE 3298 Géosystèmes (CNRS) for providing financial support curves and sea-level curves in the hirundo graptolite biozone, for a post-doctoral visit at the University of Lille 1. This is a Huanghuachang section confirm the model suggested by Molyneux contribution to the International Geoscience Programme ‘Ordovician (2009) that diversity increases in offshore locations during sea-level Palaeogeography and Palaeoclimate’ (IGCP 503) and to the SYSTER fall due to offshore migration of assemblages. Conversely, high project “Ordovician climate” (INSU, CNRS). diversity coincides with high sea level in the hirundo graptolite biozone of the Honghuayuan section (Fig. 11A), as predicted. This References effect probably implies that acritarch diversity changes would Adrain, J.M., Edgecombe, G.D., Fortey, R.A., Hammer, Ø., Laurie, J.R., McCormick, T., respond to which environmental facies the sections located in. Li et Owen, A.W., Waisfeld, B.G., Webby, B.D., Westrop, S.R., Zhou, Zhiyi, 2004. Trilobites. al. (2004) discussed the inshore–offshore diversity gradient in the In: Webby, B.D., Paris, F., Droser, M.L., Percival, I.G. (Eds.), The Great Ordovician Yangtze Platform during the deflexus to suecicus graptolite biozones Biodiversification Event. Columbia University Press, New York, pp. 231–254. Bergström, S.T., Chen, Xu, Gutiérrez-Marco, J.C., Dronov, A., 2009. The new and indicated that the most diverse assemblages occur in offshore chronostratigraphic classification of the Ordovician System and its relations to 13 shelf environments, whereas lower diversity assemblages appear in major regional series and stages and to δ C chemostratigraphy. Lethaia 42, 97–107. nearshore environments. In fact, the acritarch diversities in the Brocke, R., 1997a. Evaluation of the Ordovician acritarch genus Ampullula Righi. Annales – Huangnitang section imply that lower diversity assemblages also de la Société Géologique de Belgique 120 (1), 73 98. Brocke, R., 1997b. Palynomorpha (Acritarchen, Prasinophyceae, Chlorophyceae) aus occur in deepwater basinal environments during the deflexus to dem Ordovizium der Yangtze-Plattform, Sudwest-China. Technische Universität, suecicus graptolite biozones in South China. Berlin, Germany, PhD thesis. Brocke, R., Fatka, O., Servais, T., 1997. A review of the Ordovician acritarchs Aureotesta and Marrocanium. Annales de la Société Géologique de Belgique 120 (1), 1–22. Brocke, R., Li, Jun, Wang, Yi., 1999. Preliminary results on upper “Arenigian” to lower 5. Conclusion “Llanvirnian” acritarchs from South China. Acta Universitatis Carolinae Geologica 43 (1/2), 259–261. – Brocke, R., Li, Jun, Wang, Yi., 2000. Upper Arenigian to lower to lower Llanvirnian In summary, the total acritarch diversities of the Early Middle acritarch assemblages from South China: a preliminary evaluation. Review of Ordovician in South China increase until the suecicus graptolite Palaeobotany and Palynology 113, 27–40. biozone indicating a major acritarch radiation. The Ordovician Chen, Xu., Rong, Jiayu, Wang, Xiaofeng, Wang, Zhihao, Zhang, Yuandong, Zhan, Renbin, 1995. Correlation of Ordovician rocks of China. International Union of Geological acritarch origination curves also infer that this acritarch radiation Sciences Publication 31, 1–104. event happened with increasing disparities of acritarch forms in the Chen, Xu., Zhou, Zhiyi, Rong, Jiayu, Li, Jun, 2001. Ordovician series and stages in Chinese lower Floian in South China. The variation of the Ordovician acritarch stratigraphy: steps toward a global usage. Alcheringa 25, 131–141. Chen, Xu., Rong, Jiayu, Zhou, Zhiyi, 2003. Ordovician biostratigraphy of China. In: Zhang, diversity changes from the six sections investigated here suggests that Wentang, Chen, Peiji, Palmer, A.R. (Eds.), Biostratigraphy of China. Science Press, the acritarch diversity changes would be related to local environment Beijing, pp. 121–171. and sea-level changes. Cooper, R.A., 2004. Measures of diversity. In: Webby, B.D., Paris, F., Droser, M.L., Percival, fi Several diversity curves of fossil invertebrate groups of the Early– I.G. (Eds.), The Great Ordovician Biodiversi cation Event. Columbia University Press, New York, pp. 52–57. Middle Ordovician can be partly compared with the acritarch diversity Fang, Xiaosi, 1986a. Ordovician micropalaeoflora in Kunming–Luquan region. Yunnan curves in South China. The diversity curves of chitinozoans, Province and its stratigraphical significance. Professional Papers of Stratigraphy – conodonts, graptolites and brachiopods all show peaks during the and Palaeontology 16, 125 172 (in Chinese with English abstract). – Fang, Xiaosi, 1986b. New Lower Ordovician microplant genera and species in Ercun, Early Middle Ordovician. The trilobite diversity curve shows no Kunming, Yunnan Province. Bulletin of the Institute of Geology, Chinese Academy obvious diversity peak during the Early–Middle Ordovician. The of Geological Sciences 14, 155–158 (in Chinese with English abstract). diversity peaks of the conodonts and brachiopods appear a little Fang, Xiaosi, 1990. Ordovician microflora from Ningqiang (Shaanxi) and Guangyuan (Sichuan) and its sedimentary environment. Professional Papers of Stratigraphy earlier than that of the acritarchs, while that of the chitinozoans and Palaeontology 23, 170–185 (in Chinese with English abstract). appears a little later. The diversity curve of the graptolites shows two Fu, Jiayuan, 1986. The Ordovician group of micropalaeoflora from Xiliangsi and peaks during the Early–Middle Ordovician. The Early–Middle Ordo- Jiancaogou Formation of Zhenba, Shaanxi. Bulletin Xi'an Institute Geology Mineral Resource, Chinese Academy of Geological Sciences 12, 113–128 (in Chinese with vician diversity curves of the acritarchs, chitinozoans, conodonts, English abstract). graptolites, brachiopods and trilobites show therefore slightly Gao, Lianda, 1991. Acritarchs from the Lower Ordovician Hongshiya Formation of different evolutionary patterns which would imply that the different Wuding, Yunnan. Geological Review 37 (5), 445–455 (in Chinese with English abstract). organisms evolve with different macroevolutionary patterns in South Hammer, Ø., Harper, D.A.T., Ryan, P.D., 2001. PAST: palaeontological statistics software China. package for education and data analysis. Palaeontologia Electronica 4 (1), 1–9. The acritarch diversity changes from four sections can partly be Harper, D.A.T., 2006. The Ordovician biodiversification: setting an agenda for marine – compared to the local sea-level changes in South China but additional life. Palaeogeography, Palaeoclimatology, Palaeoecology 232, 148 166. He, Shengce, 1998. Early Ordovician acritarchs from the Well Ha i-4 in Tonghaikou area research is needed to understand the pattern, including the inshore– of Jianghan Basin, Hubei. Journal of Jiang Han Petroleum Institute 20 (1), 19–21 (in offshore trends. The diversity of acritarchs increased rapidly during Chinese with English abstract).. the Early–Middle Ordovician, perhaps because of the spreading of Hints, O., Delabroye, A., Jaak Nõlvak, J., Servais, T., Uutela, A., Wallin, Å., 2010. Biodiversity patterns of Ordovician marine microphytoplankton from Baltica: continental masses and increasing habitat space with rising sea levels. comparison with other fossil groups and sea-level changes. Palaeogeography, To perfect the present dataset, more detailed diversity studies on Palaeoclimatology, Palaeoecology 294, 161–173. acritarchs and other fossil groups, as well as more precise sea-level Hu, Yunxu, 1986. Micropalaeoflora from the Early Ordovician in Gaoqiao Region of Shaanxi and its stratigraphic significance. Bulletin of Xi'an Institute of Geology and studies, are needed to understand the Ordovician ecosystem in South Mineral Resources, Chinese Academy of Geological Sciences 14, 199–239 (in China. Chinese with English summary). K. Yan et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 299 (2011) 318–334 333

Huang Fei, 1991. Acritarchs from the Azygograptus suecicus Zone of the Ningguo Stage in Servais, T., Harper, D.A.T., Li, Jun, Munnecke, A., Owen, A.W., Sheehan, P., 2009. the Yushan area, Jianxi Province. Nanjing University, Nanjing, China, Master Thesis. Understanding the Great Ordovician Biodiversification Event (GOBE): influences of (in Chinese with English summary). palaeogeography, palaeoclimate or palaeoecology? GSA Today 19, 4–10. Huang, Fei, Zhang, Zhongying, Xiao, Chengxie, 1994. Acritarchs from the Azygograptus Servais, T., Owen, A.W., Harper, D.A.T., Kröger, B., Munnecke, A., 2010. The Great suecicus Zone of the Ningguo Stage in Yushan area, Jiangxi Province. Journal of Ordovician Biodiversification Event (GOBE): the palaeoecological dimension. Nanjing University (Earth Sciences) 6 (4), 402–411 (in Chinese with English Palaeogeography, Palaeoclimatology, Palaeoecology 294, 99–119. abstract). Smith, A.B., 2007. Marine diversity through the Phanerozoic: problems and prospects. Li, Jun, 1987. Ordovician acritarchs from the Meitan Formation of Guizhou Province, Journal of the Geological Society 164, 731–745. south-west China. Palaeontology 30 (3), 613–634. Strother, P.K., 1996. Acritarchs. In: Jansonius, J., Mcgregor, D.C. (Eds.), Palynology: Li Jun, 1989. Early Ordovician Mediterranean province acritarchs for Upper Yangtze Principles and Applications, vol. 1. American Association of Stratigraphic Region, China. In: Chinese Academy of Science (Eds.), Developments in Geoscience: Palynologists Foundation, Publishers Press, Salt Lake City, Utah, pp. 81–106. contribution to the 28th Geological Congress 1989, Washington, D.C., U.S.A. Science Su, Wenbo, 2001. On the Ordovician Sequence Stratigraphy and Sea-level Changes at Press, Beijing, pp. 231–234 the Southeast Margin of the Upper Yangtze Platform. Geological Publishing House, Li, Jun, 1990a. The discovery of acritarch in Early Ordovician from Hunan. Hunan Beijing. (in Chinese). Geology 9 (1), 8–12 (in Chinese with English abstract). Sun, Shufen, 1999. The Ordovician microflora in Yunxi, Hubei. Acta Geoscientia Sinica Li, Jun, 1990b. Ordovician acritarchs from the Jiuxi Formation of Jishou, Hunan. Acta 20 (1), 105–110 (in Chinese with English abstract). Micropalaeontologica Sinica 7 (2), 141–161 (in Chinese with English abstract). Tappan, H., Loeblich Jr., A.R., 1973. Evolution of the oceanic plankton. Earth-Science Li Jun, 1991. The Early Ordovician acritarchs from Southwest China. Nanjing Institute of Reviews 9, 207–240. Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China, PhD Tipper, J.C., 1979. Rarefaction and rarefiction — the use and abuse of a method in Thesis. (in Chinese with English summary). palaeoecology. Paleobiology 5, 423–434. Li, Jun, Yuan, Xunlai, 1998. Arenigian acritarchs from the Chaochiapa Formation of Tongiorgi, M., Yin, Leiming, Di Milia, A., 1995. Arenigian acritarchs from the Daping Ningqing County, Shaanxi Province. Acta Micropalaeontologica Sinica 15 (3), section (Yangtze Gorges area, Hubei Province, Southern China) and their 272–285 (in Chinese with English abstract). palaeogeographic significance. Review of Palaeobotany and Palynology 86, 13–48. Li, Jun, Servais, T., 2002. Ordovician acritarchs of China and their utility for global Tongiorgi, M., Yin, Leiming, Di Milia, A., Ribecai, C., 1998. Changing palaeogeographical palaeobiogeography. Bulletin de la Société Géologique de France 173, 399–406. affinities of the acritarch assemblages throughout the Dawan Formation (Arenig, Li, Jun, Yan, Kui, 2006. Radiation of Early–Middle Ordovician acritarchs in South China. Yichang Area, South China). Palynology 22, 181–196. In: Rong, Jiayu, Fang, Zongjie, Zhou, Zhonghe, Zhan, Renbin, Wang, Xiangdong, Tongiorgi, M., Yin, Leiming, Di Milia, A., 2003. Lower Yushangian to Zhejiangian Yuan, Xunlai (Eds.), Originations, Radiations and Biodiversity Changes — Evidence palynology of the Yangtze Gorges area (Daping and Huanghuachang sections), from the Chinese Fossil Record. Science Press, Beijing, pp. 317–333. 871–873 (in Hubei Province, South China. Palaeontographica Abteilung B 266, 1–160. Chinese with English abstract). Vecoli, M., Le Hérissé, A., 2004. Biostratigraphy, taxonomic diversity and patterns of Li, Jun, Wang, Yi., Brocke, R., 2000. Ordovician acritarchs from the Shihtzupu Formation morphological evolution of Ordovician acritarchs (organic-walled microphyto- of Tongzi, Guizhou. Acta Micropalaeontologica Sinica 17 (1), 30–38 (in Chinese plankton) from the northern Gondwana margin in relation to palaeoclimatic and with English abstract). palaeogeographic changes. Earth-Science Reviews 67, 267–311. Li, Jun, Wang, Yi., Servais, T., Brocke, R., 2002a. Ordovician acritarchs from Meitan Wang, Xiaofeng, Chen, Xiaohong, 2004. Ordovician chitinozoan diversification events in Formation of Huanghuachong, Guizhou, South China. Acta Palaeontologica Sinica China. Science in China (Series D) 47 (10), 874–879. 41 (1), 95–102 (in Chinese with English abstract). Wang, Zhihao, Wu, Rongchang, 2007. Ordovician conodont diversification of Yichang, Li, Jun, Servais, T., Brocke, R., 2002b. Chinese Palaeozoic acritarchs: review and Hubei Province. Acta Palaeontologica Sinica 46 (4), 430–440 (in Chinese with perspectives. Review of Palaeobotany and Palynology 118, 181–193. English abstract). Li, Jun, Brocke, R., Servais, T., 2002c. The acritarchs of the South Chinese Azygograptus Webby, B.D., Paris, F., Droser, M.L., Percival, I.G. (Eds.), 2004a. The Great Ordovician suecicus graptolite Biozone and their bearing on the definition of the Lower–Middle Biodiversification Event. Columbia University Press, New York. Ordovician boundary. Comptes Rendus Palevol 1, 75–81. Webby, B.D., Cooper, R.A., Bergström, S.M., Pairs, F., 2004b. Stratigraphic frame-work Li, Jun, Servais, T., Yan, Kui, Zhu, Huaicheng, 2004. A nearshore–offshore trend in the and time slices. In: Webby, B.D., Paris, F., Droser, M.L., Percival, I.G. (Eds.), The acritarch distribution of the Early–Middle Ordovician of the Yangtze Platform, Great Ordovician Biodiversification Event. Columbia University Press, New York, South China. Review of Palaeobotany and Palynology 130 (1–4), 141–161. pp. 41–47. Li, Jun, Servais, T., Yan, Kui, Su, Wenbo, 2007. Microphytoplankton diversity curves of Wu, Rongchang, Percival, I.G., Zhan, Renbin, 2010. Biodiversification of Early to Middle the Chinese Ordovician. Bulletin de la Société Géologique de France 178 (5), Ordovician conodonts: a case study from the Zitai Formation of Anhui Province, 399–409. eastern China. Alcheringa 34, 75–86. Li, Jun, Servais, T., Yan, Kui, 2010. Acritarch biostratigraphy of the Lower–Middle Xing, Yusheng, 1980. Microplants and chitinozoans from the Lower Ordovician Ordovician boundary (Dapingian) at the Global Stratotype Section and Point Dachengsi Formation of Emeishan, Sichuan. Fifth International Palynological (GSSP), Huanghuachang, South China. Newsletter on Stratigraphy 43 (3), Conference Abstracts. Cambridge, England, p. 438. 235–250. Xing, Yusheng, Liu, Guizhi, 1985. Microflora from the Ordovician and Silurian in the Liu, Jianbo, 2006. Sea-level changes during the Early–Mid Ordovician radiation of South Xilingxia region, Yangzi Gorges. Selected Papers from the 1st National Fossil Algal China. In: Rong, Jiayu, Fang, Zongjie, Zhou, Zhonghe, Zhan, Renbin, Wang, Xiangdong, Symposium, Beijing, pp. 145–154 (in Chinese). Yuan, Xunlai (Eds.), Originations, Radiations and Biodiversity Changes — Evidence Xu, Wanhong, 1995. Discovery of Arenigian acritarchs from Sandu, Guizhou and its from the Chinese Fossil Record. Science Press, Beijing, pp. 335–360. 875–877 (in geological significance. Acta Micropalaeontologica Sinica 12 (3), 285–292 (in Chinese with English abstract). Chinese with English abstract). Lu, Lichang, 1987. Acritarchs from the Dawan Formation (Arenigian) of Huanghua- Xu, Wanhong, 1996. Two new species of Striatotheca (acritarch) from Arenigian chang in Yichang, western Hubei. Acta Micropalaeontologica Sinica 4 (1), 87–102 Tonggao Formation of Sandu area, Guizhou Province. Acta Palaeontologica Sinica (in Chinese with English abstract). 26 (2), 496–499 (in Chinese with English abstract). Molyneux, S.G., 2009. Acritarch (marine microphytoplankton) diversity in an Early Xu, Wanhong, 1999. Acritarchs from the Etagraptus approximatus Biozone of Arenigian Ordovician deep-water setting (the Skiddaw Group, northern England): implica- in the Sandu Area of Guizhou Province. Acta Micropalaeontologica Sinica 16 (1), tions for the relationship between sea-level change and phytoplankton diversity. 61–75 (in Chinese with English abstract). Palaeogeography, Palaeoclimatology, Palaeoecology 275, 59–76. Xu, Wanhong, 2001. Acritarchs and Its Organic Stratigeochemistry from the Arenigian Paris, F., Achab, A., Asselin, E., Chen, Xiaohong, Grahn, Y., Nõlvak, J., Obut, O., in the Sandu Area. China University of Mining and Technology Press, Xuzhou. Samuelsson, J., Sennikov, N., Vecoli, M., Verniers, J., Wang, Xiaofeng, Winchester- Xu Wanhong, You Jianju, 2001. Discovery of Early Ordovican acritarchs from the Seeto, T., 2004. Chitinozoans. In: Webby, B.D., Paris, F., Droser, M.L., Percival, I.G. Ningguo Formation in Yushan area, Jiangxi Province, and its geological significance. (Eds.), The Great Ordovician Biodiversification Event. Columbia University Press, Acta Scientiarum Naturalium Universitatis Sunyatseni 40 (1), 101–104,111 (in New York, pp. 294–311. Chinese with English abstract). Playford, G., Ribecai, C., Tongiorgi, M., 1995. Ordovician acritarch genera Peteino- Xu, Wanhong, Zhang, Zhongying, Huang, Jiewen, Zhang, Haifeng, 1995. Discovery of sphaeridium, Liliosphaeridium, and Cycloposphaeridium: morphology, taxonomy, Arenigian acritarchs from Sandu, Guizhou and its geological significance. Acta biostratigraphy, and palaeogeographic significance. Bollettino della Società Micropalaeontologica Sinica 12 (3), 285–292 (in Chinese with English abstract). Palaeontologica Italiana 34, 3–54. Xu, Wanhong, Yin, Leiming, Guo, Fusheng, Peng, Huaming, 2002. The discovery and the Raup, D.M., 1976. Species diversity in the Phanerozoic; an interpretation. Paleobiology geological significance of acritarchs the Ningguo Formation in Jiangshan area, 2, 289–297. Zhejiang Province. Journal of East China Geological Institute 25 (1) 6–8 (in Chinese Rong, Jiayu, Fan, Junxuan, Miller, R.I., Li, Guoxiang, 2007. Dynamic patterns of latest with English abstract). Proterozoic–Palaeozoic–early Mesozoic marine biodiversity in South China. Yan, Kui, Li, Jun, 2005. Ordovician biostratigraphy of acritarchs from the Meitan Geological Journal 42, 431–454. Formation of Honghuayuan Section, Tongzi, Guizhou, Southwest China. Journal of Servais, T., Jun, Li., Molyneux, S., Raevskaya, E., 2003. Ordovician organic-walled Stratigraphy 29 (3), 236–256 (in Chinese with English abstract). microphytoplankton (acritarch) distribution: the global scenario. Palaeogeogra- Yan, Kui, Li, Jun, 2010. The palaeoenvironmental implication of Early–Middle phy, Paleoclimatology, Palaeoecology 195, 149–172. Ordovician acritarch communities from South China. Chinese Science Bulletin 55 Servais, T., Li, Jun, Stricanne, L., Vecoli, M., Wicander, R., 2004. Acritarchs. In: Webby, B.D., (10), 957–964. Paris, F., Droser, M.L., Percival, I.G. (Eds.), The Great Ordovician Biodiversification Yan, Kui, Li, Jun, Liu, Jianbo, 2005. Biodiversity of Early–Middle Ordovician acritarchs Event. Columbia University Press, New York, pp. 348–360. and sea level changes in South China. Chinese Science Bulletin 50 (20), Servais, T., Lehnert, O., Li, Jun, Mullins, G.L., Munnecke, A., Nützel, A., Vecoli, M., 2008. 2362–2368. The Ordovician Biodiversification: revolution in the oceanic trophic chain. Lethaia Yan Kui, Servais, T., Li Jun, 2010. Revision of the Ordovician acritarch genus Ampullula 41, 99–109. Righi 1991. Review of Palaeobotany and Palynology. 163, 11–25. 334 K. Yan et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 299 (2011) 318–334

Yin, Leiming, 1994. New forms of acritarchs from early Ordovician sediments in Zhang, Yunbai, Zhou, Zhiyi, Zhang, Junming, 2002. Sedimentary differentiation during Yichang, Hubei, China. Acta Micropalaeontologica Sinica 11, 41–53 (in Chinese with the latest early Ordovician–earliest Darriwilian in the Yangtze block. Journal of English abstract). Stratigraphy 26 (4), 302–314 (in Chinese with English abstract). Yin, Leiming, 1995. Early Ordovician acritarchs from Hunjiang region, Jilin, and Yichang Zhang, Yuandong, Chen, Xu., Goldman, D., 2007. Diversification patterns of Early and region, Hubei, China. Palaeontologia Sinica n. Series A 185 (12) 1–170 (in Chinese Mid Ordovician graptolites in South China. Geological Journal 42, 315–337. with English summary). Zhong, Guofang, 1981. Early Ordovician microflora from the Dawan Formation at Yin, Leiming, Playford, G., 2003. Middle Ordovician acritarchs from the global stratotype Huanghuachang Yichang. Bulletin Yichang Institute Geology Minerals and section of Huangnitang in Changshan, Zhejiang, China. Acta Palaeontologica Sinica Resources, Chinese Academy Geology Science Special Issue 118–126 (in Chinese 42 (1), 89–103 (in English with Chinese abstract). with English abstract). Yin, Leiming, Di Milia, A., Tongiorgi, M., 1998. New and emended acritarch taxa from the Zhong, Guofang, 1987. Microflora. In: Wang, Xiaofeng, Ni, Shizhao, Zeng, Qingluan, Xu, lower Dawan Formation (lower Arenig, Huanghuachang Section, South China). Guanghong, Zhou, Tianmei, Li, Zhihong, Xiang, Liwen, Lai, Caigeng (Eds.), Review of Palaeobotany and Palynology 102, 223–248. Biostratigraphy of the Yangtze Gorge Area (2) Early Palaeozoic Era. Geological Zhan, Renbin, Rong, Jiayu, Chen, Jinhui, Chen, Pengfei, 2005. Early–mid Ordovician Publishing House, Beijing, pp. 38–42 (in Chinese). brachiopod diversification in South China. Science in China (Series D) 48 (5), Zhou, Zhiyi, Yuan, Wenwei, Zhou, Zhiqiang, 2007. Patterns, processes and likely causes 662–675. of the Ordovician trilobite radiation in South China. Geological Journal 42, 297–313. Zhan, Renbin, Jin, Jisuo, Rong, Jiayu, 2006. β-Diversity fluctuations in Early–Mid Ordovician brachiopod communities of South China. Geological Journal 41, 271–288.